DESCRIPTION (Taken from the applicants abstract): Glucocorticoid-induced bone disease is an under addressed and potentially devastating problem in the pediatric population. Less than half of the patients on chronic steroid therapy will sustain at least one non-traumatic fracture. In addition, glucocorticoid therapy during childhood may reduce peak bone mineral density, increasing the risk of osteoporotic fractures later in life. Although bisphosphonates appear to be effective at preventing glucocorticoid induced bone loss in adults, the safety and efficacy, of these drugs for the treatment glucocorticoid induced bone disease in children is not known. Children are unique due to the potential adverse effects on growing bone. The long-term objectives of this study are to determine if a bisphosphonate, pamidronate, can be safely and effectively used to treat and prevent glucocorticoid mediated bone loss in children. Specific aim 1 is designed to test the hypothesis that pamidronate in combination with calcium and vitamin D is more effective then calcium and vitamin D alone at treating existing glucocorticoid induced bone disease. It is a 24-month single-blind, placebo-controlled study. Specific aim 2 is designed to test the hypothesis that pamidronate in combination with calcium and vitamin D, initiated within 90 days of initiating glucocorticoid therapy, is more effective then calcium and vitamin D alone at preventing a decrease in bone density in children anticipated to require long term glucocorticoid therapy. It is a 12-month single- blind, placebo-controlled study with a 12-month post-treatment follow-up period. The primary endpoint of specific aim 1 and 2 is volume corrected lumbar spine bone mineral density (BMD). Secondary endpoints include proximal femur and whole body BMD, fractures, markers of bone turnover, growth, and skeletal changes.